Hello, any one help me, How can I write the expression and statements for these equations

how can I write intervals in matlab

kt= G/G_o

for this condition:

G_d = G*(1-0.09*kt) for kt < 0.22
G_d = G*(0.9511-0.1604*kt+4.388*kt^2-16.638*kt^3+12.336*kt^4) for 0.22<=kt<=0.8
G_d = G*0.165 for k < 0.8

Answer 1

[Azzi Abdelmalek]

G=1
kt=0:0.01:1
idx1=kt<0.22
idx2=kt>=0.22 & kt<0.8
idx3=kt>=0.8
G_d(idx1) = G*(1-0.09*kt(idx1))
G_d(idx2)=  G*(0.9511-0.1604*kt(idx2)+4.388*kt(idx2).^2-16.638.*kt(idx2).^3+12.336.*kt(idx2).^4)
G_d(idx3) = G* 0.165

Answer 2

[dpb]

Just as it's given, pretty much...

G_d = function(G,kt)
if kt<0.22
  G_d = G*(1-0.09*kt);
elseif 0.22<=kt<=0.80
  G_d = G*polyval([12.336 -16.638 4.388 -0.1604 0.9511],kt);
else
  G_d = G*0.165;
end

This assumes the last "<" should've been ">" in the original problem statement; otherwise the conditions are inconsistent.

Also assumes kt is a single value, not a vector--in that case use logical addressing and array syntax.

Answer 3

[Star Strider]

Another approach:

G = linspace(0, 1);                                         % Create Data
G_o = 0.5;                                                  % Create Data

kt= G/G_o;
G_d1 = @(kt) G.*(1-0.09*kt);
G_d2 = @(kt) G.*(0.9511-0.1604*kt+4.388*kt.^2-16.638*kt.^3+12.336*kt.^4);
G_d3 = @(kt) G*0.165;    

G_d = @(kt) G_d1(kt).*(kt < 0.22) + G_d2(kt).*((0.22 <= kt) & (kt <= 0.8)) + G_d3(kt).*(kt > 0.8);

figure(1)
plot(kt, G_d(kt))
grid